From owner-freebsd-net@FreeBSD.ORG Sat Jan 22 01:07:36 2005 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id EE18416A4CE for ; Sat, 22 Jan 2005 01:07:36 +0000 (GMT) Received: from drumandbass.at (drumandbass.at [62.116.16.204]) by mx1.FreeBSD.org (Postfix) with ESMTP id C074343D46 for ; Sat, 22 Jan 2005 01:07:35 +0000 (GMT) (envelope-from chaoztc@confusion.at) Received: (qmail 5548 invoked by uid 1027); 22 Jan 2005 01:07:34 -0000 Received: from 62.116.16.204 by drumandbass.at (envelope-from , uid 82) with qmail-scanner-1.23st (spamassassin: 2.63. perlscan: 1.23st. Clear:RC:1(62.116.16.204):. Processed in 3.342001 secs); 22 Jan 2005 01:07:34 -0000 X-Qmail-Scanner-Mail-From: chaoztc@confusion.at via drumandbass.at X-Qmail-Scanner: 1.23st (Clear:RC:1(62.116.16.204):. Processed in 3.342001 secs Process 5539) Received: from unknown (HELO drumandbass.at) (62.116.16.204) by drumandbass.at with SMTP; 22 Jan 2005 01:07:30 -0000 Date: Sat, 22 Jan 2005 02:07:29 +0100 (CET) From: Ingo X-X-Sender: To: Brooks Davis In-Reply-To: <20050121230726.GB18608@odin.ac.hmc.edu> Message-ID: <20050122020040.J93890-100000@ix.reflection.at> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII cc: "freebsd-net@freebsd.org" Subject: Re: [PATCH] 802.1p priority (fixed) X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 22 Jan 2005 01:07:37 -0000 Hi > > In an Isp backbone I trust 802.1Q packets because no customer has access > > to tagged vlan connections. > > Trusting in TOS bit is in such a network no good idea because every > > customer could send IP traffic. And overwriting the TOS bit at all network > > edges could be a pain to not miss some edges. > > 802.1Q is some kind of "out of band" QOS for IP. > > > > L2 Ethernet switches could also handle 802.1Q but not the TOS bits in the > > IP header. > > I'm not sure what your point is. It's certaintly the case that they are > only useful if you trust all hosts on the ethernet. Untagged ethernet could be untrusted because 802.1Q is only possible on tagged ethernet. The priority tag is an extension to the 802.1P vlan header. In an ISP environment there are in most time routing hops between which effecively kill the 802.1Q field. Only easy to select ip-interfaces on more intelligent hardware (L3 switches, ...) could pass the data over routing hops, which are much easier to control than ip routing modems which could easily be hijacked by customers. Also not much modem support the changing of the TOS field. In short wortds: 802.1Q is easy to control and easy to secure. TOS, DSCP, ... is easy to control but hard to secure. bye, Ingo